Returns an anonymous function.
lambda variable, …: expression
- variable, …
- Optional. One or more variables used in the right part of the expression.
- Required. Return value of the function.
lambda expression is a shorthand way of defining a function that is not bound to a specified name during its creation.
Consider the following function:
>>> def func(a): return a + 1 ... >>> func(0) 1 >>>
The same function can be defined using lambda expression as follows:
>>> func = lambda a: a + 1 >>> func(0) 1
Both functions are the same. Note that lambda does not include a return statement. The right expression is the implicit return value. Lambda functions need not to be assigned to any variables.
>>> # this example shows how to use lambda with sorted function >>> # lambda function is grabage collected after it has been used >>> # (there is no reference to it to keep it alive) >>> sorted(['A', 'b', 'C'], key=lambda x: x.lower()) ['A', 'b', 'C']
>>> # this is a code snippet from a Tkinter gui app >>> # in this case lambda is quite convenient >>> self.btn_cancel = Button(self.progress_container, text='Cancel', >>> command=lambda: subprocess.call('taskkill /f /im uberzip.exe', >>> shell=True))